1. Technical Field
This invention relates to a counter assembly for use in conjunction with a fluid meter to provide flow volume information corrected to a standard. In particular, the invention is concerned with an improvement in the arrangement for mounting a clutch on an output shaft connected between a mechanical computer utilized in correcting a measure of actual flow and a register providing corrected flow volume information.
2. Background Information
Gas meters include counters with mechanical computers for correcting a measured volume of gas which flows through the meter to accommodate for volumetric differences from a standard volume at a standard set of conditions. One form of prior meter counter including a mechanical computer for making corrections due to the temperature differences from a standard temperature is disclosed in U.S. Pat. No. 3,581,566. As disclosed in that patent, a compensating device includes a temperature sensitive transducer including a cam which serves to limit travel of the end of a driven arm. A one-way clutch translates arcuate advance and return strokes of the driven arm into rotation of an output shaft which, in turn, is connected to a meter register. The driven arm is moved by an eccentric mechanism which is connected to a shaft rotated in proportion to the actual volume of flow through the meter. The position of the cam and hence the travel of the driven arm is variable dependent upon temperature. Within the mechanism connecting the driven arm to the meter is an overtravel spring which acts between parts of the mechanism to provide for relative differences in travel between the corrected rotational output and the uncorrected rotational input when the driven arm engages the temperature cam. During overtravel, the overtravel spring functions to return parts to an initial setting, acting at least partially against an input hub of the clutch to maintain contact of the driven arm against the cam and to maintain disengagement of the input hub from the output shaft of the mechanical computer except when the driven arm is moved away from the cam. Thus, the driven arm acting through the one-way clutch produces a temperature corrected rotational output from an uncorrected rotational input.
Space limitations in meter counters may dictate that an input hub of the one-way clutch be drivingly connected to the output shaft and loaded from the side, that is to say from outside of the plane of rotation of the input hub. With clutches which utilize spring biased rollers for one-way gripping, this side loading can sometimes cause the hub to twist and the rollers to bind and possibly stick between the hub and the output shaft. As a result, the hub will not free wheel relative to the output shaft and return to its start position. This results in the introduction of measurement inaccuracies into the output of the mechanical computer.
In prior meter counters which utilize an overtravel spring between parts of the counter to provide for relative differences in travel between corrected rotational output and uncorrected rotational input, a stronger overtravel spring may be utilized to overcome clutch binding. However, the strength of the overtravel spring has a direct effect on the drag of the meter rotor, the stronger the spring the greater the drag, and an attendant reduction in the accuracy of the measured volume of flow through the meter particularly at low volume flow rates.